REVIEW ARTICLE Techniques and principles of tuberosity fixation for proximal humeral fractures treated with hemiarthroplasty Mark A. Frankle, MD, and Mark A. Mighell, MD, Tampa, FL INTRODUCTION In 1970 Neer 42,43 first published his results on humeral head replacement for proximal humeral frac- tures. During the past 3 decades, our ability to treat these fractures with arthroplasty has evolved as a result of our better understanding of proximal humeral anatomy, innovations in prosthetic design, and metic- ulous surgical technique. Fracture reduction with sta- ble internal fixation is a basic surgical principle for all fractures. When this is achieved, early mobilization of the injured extremity can minimize joint stiffness and muscle atrophy. When prosthetic arthroplasty is the preferred treatment of a proximal humeral frac- ture, correct height and version are necessary with cement fixation of the stem. Many fracture systems now incorporate internal and external guides that can help place the prosthesis in correct version and height. The current challenge is to restore proximal humeral geometry with stable internal fixation of the tuberosities. At present, tuberosity complications ac- count for the majority of early failures and poor outcomes (Table I and Table II). This article reviews the pertinent anatomic landmarks that help achieve a proper reduction of the tuberosities and defines the biomechanical and clinical consequences of mal- union and nonunion. GEOMETRY OF THE PROXIMAL HUMERUS Iannotti et al 25 studied the anatomy of the proximal humerus in 100 cadaveric shoulders. They reported that the head-to-tuberosity distance was 8  3 mm (range, 3-20 mm) and the greater tuberosity was always below the superior-most aspect of the humeral head. They also investigated the lateral offset (the distance from the base of the coracoid to the lateral- most point of the greater tuberosity) and found that this distance correlated to the size of the humeral head (Figure 1). These relationships must be restored to optimize the mechanics of the attached muscle tendon units. The appropriate thickness of the head segment also can be templated preoperatively by measuring the lateral offset of the uninvolved side. Head sizing is critical to allow for appropriate tension within the joint capsule. 26 Boileau et al 5,7 demonstrated, in 65 humeri, sig- nificant variations in humeral version and posterome- dial offset of the head segment with respect to the humeral shaft (Figure 2). When the proximal humerus is fractured, loss of normal landmarks makes it difficult to identify these variations intraoperatively. Further- more, the variability between individual humeri with respect to posteromedial offset may make this param- eter irrelevant in this type of surgery. There are cur- rently no clinical studies that have analyzed the results of standard versus offset heads. Although there exists substantial variation in humeral retroversion, most surgeons consider 20° to 40° as an acceptable range for implant replacement. 5,7,48 FRACTURE PATTERN AND DEFORMING FORCES Fractures of the proximal humerus that are best suited for hemiarthroplasty include 4-part fractures, head-splitting fractures, impaction fractures of the hu- meral head with involvement of greater than 50% of the articular surface, and 3-part fractures in elderly patients with osteoporotic bone.* The cortical bone of the greater tuberosity thickens as one moves distally to the point at which the tuber- osity becomes confluent with the shaft. 31 The quality of the proximal humeral bone must be taken into account when attempting to reduce the tuberosity fragments anatomically. 59 Other factors that affect From the Florida Orthopaedic Institute, Tampa, Fla. Reprint requests: Mark A. Frankle, MD, 4175 E Fowler Ave, Tampa, FL 33617. J Shoulder Elbow Surg 2004;13:239-47. Copyright © 2004 by Journal of Shoulder and Elbow Surgery Board of Trustees. 1058-2746/2004/$35.00 + 0 doi:10.1016/S1058-2746(02)00041-1 *References 1-4, 8, 9, 10, 11, 13, 15, 17, 21-24, 28, 33, 37, 38, 40, 42-45, 47, 53, 54, 55, 61, 63-65. 239